An IEEE 802.16m communication system which is a representative communication system based on Orthogonal Frequency Division Multiple Access (hereinafter, referred to as “OFDMA”) has a small information quantity and provides a feedback channel which can transmit an MAC header and an MAC control message for transmitting larger capacity feedback information as well as a fast feedback channel having a fixed physical structure.
In Order to instruct a mobile terminal to allocate and release the feedback channel, a feedback channel allocation message was used in the prior art. The feedback channel allocation message is used for allocating two feedback channels, that is, a long period feedback channel and a short period feedback channel to the mobile terminal.
Transmission times of feedback information between the long period channel and the short period feedback channel are different from each other. That is, the feedback information of the short period feedback channel is not transmitted at the time when the feedback information of the long period feedback channel is transmitted, and the feedback information of the long period feedback channel is not transmitted at the time when the feedback information of the short period feedback channel is transmitted.
Meanwhile, the conventional feedback channel allocation message contains only one information such as a resource index indicating a size and a position of the allocated resource, a Multiple Input Multiple Output (MIMO) transmission type, or an offset (hereinafter, referred to as “Isizeoffset”) used for calculating a buffer size index without regard to the long terminal feedback channel and the short period feedback channel.
Accordingly, even through information quantities to be transmitted using the long period feedback channel and the short period feedback channel are different, resources at the same position and having the same size are allocated to the long period feedback channel and the short period feedback channel, and transmission types used for the long period feedback channel and the short period feedback channel are the same.
Meanwhile, the IEEE 802.16m communication system determines a buffer size and a coding rate by two parameters of Resource Index and Isizeoffset. Using the same parameter for the long period feedback channel and the short period feedback channel means that zero padding should be performed to make the feedback channels have the same buffer size and the feedback information should be transmitted using the same coding rate even though information quantities to be transmitted are different.
Accordingly, when the same resource is allocated to the long period feedback channel and the short period feedback channel, the coding rate of the feedback channel having the small feedback information quantity to be transmitted unnecessarily becomes higher than an actually required coding rate.
Particularly, the long period feedback channel is used for transmitting information having higher importance in comparison with the short period feedback channel, and the information quantity transmitted through the long period feedback channel is generally small, which requires a solution to solve the above problems.